US-12625240-B2 - Systems and methods for tuning filters for use in LiDAR systems

Abstract

A LiDAR system comprising one or more tunable filters is provided. The one or more tunable filters can be tuned to compensate for wavelength shifts of light signals caused by ambient environmental changes. The LiDAR system includes a light source providing light signals, a signal steering system configured to direct the light signals to a field-of-view, and temperature monitoring circuitry configured to monitor a temperature shift of the light source. The temperature shift corresponds to a wavelength shift of the light signals from a first wavelength value to a second wavelength value. The system further comprises a tunable filter positioned in a receiving system configured to receive return light signals, and a motor configured to rotate the tunable filter by an angle based on the temperature shift such that a passband of the tunable filter matches the second wavelength value.

Inventors

• Yimin Li
• Rui Zhang
• Junwei Bao

Assignees

• INNOVUSION, INC.

Dates

Publication Date

20260512

Application Date

20230710

Claims (20)

1. 1 . A light detection and ranging (LiDAR) system, comprising: a light source providing light signals; an optical scanner configured to direct the light signals to a field of view in multiple dimensions; temperature monitoring circuitry configured to monitor a temperature shift of the light source, the temperature shift corresponding to a wavelength shift of the light signals from a first wavelength value to a second wavelength value; a tunable filter disposed in a receiving system configured to receive return light signals; and a motor configured to rotate the tunable filter by an angle based on the temperature shift such that a passband of the tunable filter matches the second wavelength value, wherein a distance to an object located in the field of view is obtained based on the return light signals and the light signals directed to the field of view.
2. 2 . The system of claim 1 , wherein the receiving system comprises at least one lens or mirror configured to converge the return light signals to pass the tunable filter.
3. 3 . The system of claim 1 , wherein the receiving system comprises a mirror configured to reflect the return light signals to the tunable filter.
4. 4 . The system of claim 3 , wherein the mirror is a flat mirror.
5. 5 . The system of claim 3 , wherein the mirror is a concave mirror.
6. 6 . The system of claim 1 , wherein the receiving system comprises a polygon mirror.
7. 7 . The system of claim 1 , wherein the tunable filter comprises a filter and a rotatable frame.
8. 8 . The system of claim 1 , wherein the motor comprises a controller configured to determine, based on a calibration between the temperature shift of the light source and a corresponding wavelength shift of the light signals, the angle to which the tunable filter is to be rotated.
9. 9 . The system of claim 8 , wherein the calibration is based on a correlation between a plurality of wavelengths and a plurality of rotation angles of the tunable filter.
10. 10 . The system of claim 1 , wherein the motor is configured to rotate the tunable filter in response to a monitored temperature shift of the light source larger than a threshold temperature shift.
11. 11 . The system of claim 10 , wherein a maximum rotation angle of the tunable filter accommodates the maximum range of the temperature shift of the light signals.
12. 12 . The system of claim 1 , wherein a rotation angle of 30 degrees of the tunable filter accommodates at least one of a maximum range of the temperature shift or a maximum range of the wavelength shift of the light signals.
13. 13 . The system of claim 1 , wherein a rotation resolution of the motor is between 0.1 to 10 degrees.
14. 14 . The system of claim 1 , wherein the tunable filter is configured to filter out at least some radiation having wavelengths different from the second wavelength value.
15. 15 . The system of claim 1 , wherein the receiving system comprises a first optic and a second optic, and wherein the tunable filter is positioned between the first and second optics.
16. 16 . The system of claim 15 , wherein the first optic comprises a collection lens.
17. 17 . The system of claim 1 , wherein the tunable filter comprises an interference filter.
18. 18 . A method comprising: monitoring a temperature shift of a light source providing light signals to a light signal scanner of a light ranging and detection (LiDAR) system, wherein the light signal scanner is configured to direct the light signals to a field of view in multiple dimensions, the temperature shift corresponding to a wavelength shift of the light signals from a first wavelength value to a second wavelength value; determining that the monitored temperature shift corresponding to a wavelength of the light signals that shifts from a first wavelength value to a second wavelength value; and actuating a motor to rotate a tunable filter by an angle based on the monitored temperature shift such that a passband of the tunable filter matches the second wavelength value, wherein the tunable filter is disposed in a receiving system configured to receive return light signals, wherein a distance to an object located in the field of view is obtained based on the return light signals and the light signals directed to the field of view.
19. 19 . The method of claim 18 , further comprising, directing, by the receiving system comprising one or more optics, the return light signals to the tunable filter.
20. 20 . The method of claim 18 , wherein directing the return light signals to the tunable filter comprises: converging, by a collection lens, the return light signals to form converged return light signals; and reflecting, by a mirror, the converged return light signals to the tunable filter.

Description

CROSS-REFERENCE TO RELATED APPLICATIONS This application is a continuation-in-part of U.S. patent application Ser. No. 16/546,724 filed Aug. 21, 2019, entitled “SYSTEMS AND METHODS FOR TUNING FILTERS FOR USE IN LIDAR SYSTEMS”, which claims the benefit of U.S. Provisional Patent Application Ser. No. 62/722,498, filed Aug. 24, 2018, entitled “SYSTEMS AND METHODS FOR TUNING FILTERS FOR USE IN LIDAR SYSTEMS”. The contents of both applications are hereby incorporated by reference in their entireties for all purposes. FIELD OF THE TECHNOLOGY This disclosure relates generally to light detection and, more particularly, to a light detection and ranging (LiDAR) system having tunable filters to improve light detection. BACKGROUND Light detection and ranging (LiDAR) systems use light signals to create an image or point cloud of the external environment. A LiDAR system may be a scanning or non-scanning system. Some typical scanning LiDAR systems include a light source, a light transmitter, a light steering system, and a light detector. The light source generates a light beam that is directed by the light steering system in particular directions when being transmitted from the LiDAR system. When a transmitted light beam is scattered or reflected by an object, a portion of the scattered or reflected light returns to the LiDAR system to form a return light signal. The light detector detects the return light signal. Using the difference between the time that the return light signal is detected and the time that a corresponding light signal in the light beam is transmitted, the LiDAR system can determine the distance to the object based on the speed of light. This technique of determining the distance is referred to as the time-of-flight (ToF) technique. The light steering system can direct light beams along different paths to allow the LiDAR system to scan the surrounding environment and produce images or point clouds. A typical non-scanning LiDAR system illuminates an entire field-of-view (FoV) rather than scanning through the FoV. An example of the non-scanning LiDAR system is a flash LiDAR, which can also use the ToF technique to measure the distance to an object. LiDAR systems can also use techniques other than time-of-flight and scanning to measure the surrounding environment. SUMMARY Embodiments provided in this disclosure use temperature monitor circuitry and tunable filters in a light detection and ranging (LiDAR) system to improve light detection and compensate for wavelength shifts caused by ambient environmental changes. In one embodiment, a LiDAR system comprising one or more tunable filters is provided. The one or more tunable filters can be tuned to compensate for wavelength shifts of light signals caused by ambient environmental changes. The LiDAR system includes a light source providing light signals, a signal steering system configured to direct the light signals to a field-of-view (FoV), and temperature monitoring circuitry configured to monitor a temperature shift of the light source. The temperature shift corresponds to a wavelength shift of the light signals from a first wavelength value to a second wavelength value. The system further comprises a tunable filter positioned in a receiving system configured to receive return light signals. The system further comprises a motor configured to rotate the tunable filter by an angle based on the temperature shift such that a passband of the tunable filter matches the second wavelength value. In one embodiment, a vehicle comprising a light detection and ranging (LiDAR) system is provided. The LiDAR system includes a light source providing light signals, and a signal steering system configured to direct the light signals to a FoV. The system further includes temperature monitoring circuitry configured to monitor a temperature shift of the light source in the vehicle. The temperature shift corresponds to a wavelength shift of the light signals from a first wavelength value to a second wavelength value. The system further includes a motor configured to rotate a tunable filter by an angle based on the temperature shift such that a passband of the tunable filter matches the second wavelength value. The tunable filter is disposed in a receiving system configured to receive return light signals. In one embodiment, a method to improve light detection in a LiDAR system is provided. The method includes monitoring a temperature shift of a light source providing light signals to a light signal scanner of a light ranging and detection (LiDAR) system. The temperature shift corresponds to a wavelength shift of the light signals from a first wavelength value to a second wavelength value. The method further includes determining that the monitored temperature shift corresponding to a wavelength of the light signals that shifts from a first wavelength value to a second wavelength value; and actuating a motor to rotate a tunable filter by an angle based on the monitored temperature